The major change is the "Quiet Hour" feature, which is among the number one asked: turn off callback completely for certain time (such as any time other than Monday-Friday, 7am-8pm).

(Those of you who like to play around with your phone probably already implemented this feature on your own with Tasker/Locale. This feature is simply here since perhaps some of you don't want to pay for an extra app to do something as simple as this. I still strongly encourage you to use Tasker/Locale to turn callback on/off based on more complex situations. More features on the plugin is forthcoming, including the ability to change the callback number with the plugin. Stay tuned!)